The appointment comes in the same week that National Express won the London-to-Scotland Inner City East Coast rail franchise from GNER in a £1.4 billion bid. The operator will run the route from December this year until 2015.
There is speculation that National Express is plotting an integrated coach and rail travel offering, and that CHI is in a good position to win the combined task.
CHI already handles ad work for the National Express Group. Hooper Galton works on the advertising for National Express' coach business. It's unclear how CHI's hiring will affect this relationship.
CHI declined to comment and National Express did not return calls.